Does a compost bin need a bottom? And other composting FAQs!

  • Date: May 14, 2022

Composting is gaining popularity year-on-year as people try to live more eco-friendly lives. As well as a great way to reduce your impact on the environment, it also provides you with a nutrient-rich compost to use in your garden. Unfortunately, composting is not as simple as popping your leftovers in a bin and hoping for the best – the materials require specific conditions to breakdown. Here we will answer a few questions about the basic compost set up.

So, does a compost bin need a bottom?

Compost bins do not need a bottom. In fact, there are several benefits of being open-bottomed. The decomposition process is speeded up since worms and microbes can get into the bin from the soil underneath. And the soil benefits too – nutrients travel from the composting material down into the soil. Your whole garden can benefit from this if you move it to different areas too. 

Open-bottomed bins work in a similar way to compost bins with a bottom – just ensure that your first layer, that lies directly on the soil is ‘green’ (nitrogen rich materials such as coffee grounds and fresh grass trimmings) before adding a ‘brown’ layer (carbon rich materials such as  dry leaves and hay). The same 1-part green to 30-parts brown ratio applies to both compost bins with and without a bottom – although, the ratio is not an exact science, experimentation is required!

Does a compost bin need to be in the sun?

Compost bins do not need to be placed in the sun. The heat can speed up the process however, heat is generated from the rotting material itself rather than it needing scorching sun. If you have limited sunny spots in your garden, it may be best to reserve these for you plants, rather than your compost pile. Being in the shade, may also be more comfortable for you when you are busy tending to the pile – it can be hard work, especially if you live in a hot climate.

If you do live in a hot climate, be sure to keep an eye out for signs of dehydration in the pile. Lack of moisture will prevent the microbes doing their job, whilst potentially also leading to your pile being overrun by ants!

Does a compost bin need a lid?

A compost bin does not need a lid – you can buy them with or without. However, a lid does bring different benefits. As well as keeping pests such as rats and mice out, it also helps you retain moisture in your pile. Moisture control is particularly important – with no lid you are at the mercy of the weather. Your pile could end up water-logged after a storm or too dry after a particularly sunny few weeks – each bringing their unique problems. Having a lid avoids this.

Does a compost bin need air holes?

Composting is an aerobic process – that is, it needs oxygen to work. Sufficient airflow is needed or the breakdown process will not occur. The contents of the pile are extremely important – if the materials are too compact, air will not be able to flow through. Adding materials such as twigs and balls of paper will create gaps to alleviate this. This is, arguably, more important than air holes.  

Do I need to turn my compost regularly?

It is commonly suggested in the gardening community that a compost pile must be turned regularly – the theory behind this is that it will creates spaces and make it less compact so that air can flow freely again. However, this can be slightly off putting if you are considering starting composting but have mobility problems or minimum time to maintain the pile.

Turning the pile is the best way to ensure air flow, however there are other alternatives. As mentioned above, having twigs and other materials that help maintain a structure with air pockets reduces the need for turning.  Alternatively, you can use a compost aerator to mix the contents of the pile or a simple garden fork.

Does compost need water?

As well as oxygen, your compost pile also needs water. The microbes need to have a sufficient level of moisture to carry out the breakdown process optimally. A rough rule of thumb is that if your pile becomes less moist that a wrung-out sponge, it needs to be watered! Be careful though, you don’t want it too wet either. Find more info about watering compost here.

Do I need to form compost pile layers?

Layering your compost pile is recommended widely in the gardening literature, especially when aiming for pile with increased temperatures. Although layering is a useful way to ensure you have the right ratio of green to brown materials, it is not strictly necessary.  

Many households simply do not produce enough food scraps, or waste in general, to use the layering method – this may put them off composting totally. Just do what you can, it does not need to be perfect, and you can learn as you go along. Even the most experienced composters are continually learning and need to tweak the way they maintain their compost pile depending on their lifestyle and waste outputs.